Korean artist Yong Ho Ji takes old tires and turns them into awesome sculptures of sharks, horses, monsters, and men. Much of his work is a warning about the dangers of genetic manipulation:

Ho’s concept of mutants grew out of his life in Seoul, where there is fierce political debate over genetic engineering. In school, Yong Ho read Darwin and was galvanized by how his theory of evolution applied to man’s manipulation with nature. Already, he says, cats and dogs are bred to emphasize their domesticated traits and downplay their wild sides. The sculptures can be taken as warnings; if we’re not careful, we may soon lose the ability to see animals in their natural state altogether.

True. Why manufacture new materials when you can use a material that's destined for repurposing as something else? Odds are, you probably don't have to pay too much (if anything!) to get your hands on some expired tires!